| Description | Jonathan Hornblower, one of the sons of the veteran Cornish engineer Jonathan Hornblower, obtained his patent for a double-cylinder or compound engine in 1781, and the first engine he erected was at Radstock Colliery, frequently spelt "Radstoke", in Somerset. The engine was working satisfactorily by the end of 1782, but Hornblower appears to have only erected two more engines in the following years; one at Timsbury near Bath, and an experimental engine at Penryn. Hornblower felt that he was not infringing Watt’s patent, but Boulton & Watt believed that he was. Boulton & Watt obtained various descriptions of the Radstock engine, which are in this bundle, but they did not pursue any legal action against Hornblower. However Watt did place an advertisement in the Bristol newspapers listing six features of his engine which, if used by other engineers, would be considered infringements of his patent. This advertisement appeared in 1782, and Watt also drafted an "Address to the Gentlemen of Cornwall contra Horners" at around the same time, which can be found in this bundle. This was written in response to Hornblower’s efforts to solicit orders from the naturally sympathetic Cornish mining industry.
This bundle contains correspondence about Hornblower’s patent and the Radstock engine. Further letters on the Radstock engine can be found in the bundle of "Additional Papers" (MS 3147/2/35). For papers relating to premiums demanded from mines that erected Hornblower’s engines, see the bundles of papers relating to Cornish Law Cases (MS 3147/2/51—MS 3147/2/60). For further drawings of Jonathan Hornblower’s engines including the Radstock engine, see "Sketches and Descriptions of Pirate and Rival Engines" (MS 3147/2/62) and "Drawings of Engine Designs by James Watt, Bull and Hornblower’s Engines, Dutch Windmill etc.", Portfolio MS 3147/5/1339b. |